I am on a job where the job spec req that home runs be sized up ,runs over 100 ft have to be #10 conductor, the rest of the circuit will be #12mc cable feeding recp loads.
This is a job spec, it is not that unusual in new and rehab. construction. It's called out all the time locally around here. It will be SOP for this building, and the owner and or maintenance department will not only
know about it but will uphold this desired aspect.
You need to do this for spec., and inspected for both the spec's. and the electrical inspection once done, your done.
Anyone following this phase of construction, altering, changing or dealing with the circuits will or should hear it like a drum beat. Besides most will figure it out very quickly!
It'll be under their license and nothing having to do with what you have done.